Methods for manufacturing wind turbine rotor blade panels having printed grid structures

ABSTRACT

A method for manufacturing a rotor blade panel of a wind turbine includes placing one or more fiber-reinforced outer skins into a mold of the rotor blade panel. The method also includes printing and depositing, via a computer numeric control (CNC) device, a plurality of rib members that form at least one three-dimensional (3-D) reinforcement grid structure onto an inner surface of the one or more fiber-reinforced outer skins. Further, the grid structure bonds to the one or more fiber-reinforced outer skins as the grid structure is deposited. Moreover, the method includes printing at least one additional feature into the grid structure.

FIELD

The present disclosure relates in general to wind turbine rotor blades,and more particularly to methods of manufacturing wind turbine rotorblade panels having printed grid structures.

BACKGROUND

Wind power is considered one of the cleanest, most environmentallyfriendly energy sources presently available, and wind turbines havegained increased attention in this regard. A modern wind turbinetypically includes a tower, a generator, a gearbox, a nacelle, and oneor more rotor blades. The rotor blades capture kinetic energy of windusing known foil principles. The rotor blades transmit the kineticenergy in the form of rotational energy so as to turn a shaft couplingthe rotor blades to a gearbox, or if a gearbox is not used, directly tothe generator. The generator then converts the mechanical energy toelectrical energy that may be deployed to a utility grid.

The rotor blades generally include a suction side shell and a pressureside shell typically formed using molding processes that are bondedtogether at bond lines along the leading and trailing edges of theblade. Further, the pressure and suction shells are relativelylightweight and have structural properties (e.g., stiffness, bucklingresistance and strength) which are not configured to withstand thebending moments and other loads exerted on the rotor blade duringoperation. Thus, to increase the stiffness, buckling resistance andstrength of the rotor blade, the body shell is typically reinforcedusing one or more structural components (e.g. opposing spar caps with ashear web configured therebetween) that engage the inner pressure andsuction side surfaces of the shell halves.

The spar caps are typically constructed of various materials, includingbut not limited to glass fiber laminate composites and/or carbon fiberlaminate composites. The shell of the rotor blade is generally builtaround the spar caps of the blade by stacking layers of fiber fabrics ina shell mold. The layers are then typically infused together, e.g. witha thermoset resin. Accordingly, conventional rotor blades generally havea sandwich panel configuration. As such, conventional blademanufacturing of large rotor blades involves high labor costs, slowthrough put, and low utilization of expensive mold tooling. Further, theblade molds can be expensive to customize.

Thus, methods for manufacturing rotor blades may include forming therotor blades in segments. The blade segments may then be assembled toform the rotor blade. For example, some modern rotor blades, such asthose blades described in U.S. patent application Ser. No. 14/753,137filed Jun. 29, 2015 and entitled “Modular Wind Turbine Rotor Blades andMethods of Assembling Same,” which is incorporated herein by referencein its entirety, have a modular panel configuration. Thus, the variousblade components of the modular blade can be constructed of varyingmaterials based on the function and/or location of the blade component.

In view of the foregoing, the art is continually seeking improvedmethods for manufacturing wind turbine rotor blade panels.

BRIEF DESCRIPTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one aspect, the present disclosure is directed to a method formanufacturing a rotor blade panel. The method includes placing a mold ofthe rotor blade panel relative to a computer numeric control (CNC)device. The method also includes forming one or more fiber-reinforcedouter skins in the mold. The method also includes printing anddepositing, via the CNC device, a plurality of rib members that form atleast one three-dimensional (3-D) reinforcement grid structure onto aninner surface of the one or more fiber-reinforced outer skins before theone or more fiber-reinforced outer skins have cooled from forming.Further, the grid structure bonds to the fiber-reinforced outer skin(s)as the structure is deposited. In addition, the plurality of rib membersinclude, at least, a first rib member extending in a first direction anda second rib member extending in a different, second direction.Moreover, the first rib member has a varying height along a lengththereof.

In another aspect, the present disclosure is directed to a method formanufacturing a rotor blade panel. The method includes placing one ormore fiber-reinforced outer skins into a mold of the rotor blade panel.The method also includes printing and depositing, via a computer numericcontrol (CNC) device, a plurality of rib members that intersect at aplurality of nodes to form at least one three-dimensional (3-D)reinforcement grid structure onto an inner surface of the one or morefiber-reinforced outer skins. Further, the grid structure bonds to theone or more fiber-reinforced outer skins as the grid structure isdeposited. Moreover, one or more heights of intersecting rib members atthe nodes are different.

In yet another aspect, the present disclosure is directed to a methodfor manufacturing a rotor blade panel. The method includes placing amold of the rotor blade panel relative to a computer numeric control(CNC) device. Further, the method includes forming one or morefiber-reinforced outer skins in the mold. The method also includesprinting and depositing, via the CNC device, at least onethree-dimensional (3-D) reinforcement grid structure onto an innersurface of the one or more fiber-reinforced outer skins before the oneor more fiber-reinforced outer skins have cooled from forming. As such,the grid structure bonds to the one or more fiber-reinforced outer skinsas the grid structure is being deposited. Moreover, the grid structureincludes at least one curved rib member.

In still another aspect, the present disclosure is directed to a methodfor manufacturing a rotor blade panel. The method includes placing oneor more fiber-reinforced outer skins into a mold of the rotor bladepanel. The method also includes printing and depositing, via a computernumeric control (CNC) device, a plurality of rib members that form atleast one three-dimensional (3-D) reinforcement grid structure onto aninner surface of the one or more fiber-reinforced outer skins. Further,the grid structure bonds to the one or more fiber-reinforced outer skinsas the grid structure is deposited. Moreover, the method includesprinting at least one additional feature into the grid structure.

In yet another aspect, the present disclosure is directed to a rotorblade panel. The rotor blade panel includes an outer surface having oneor more fiber-reinforced outer skins. Further, the rotor blade panelincludes a printed grid structure secured to an inner surface of the oneor more fiber-reinforced outer skins. The grid structure includes aplurality of rib members and at least one additional feature printedinto the grid structure. Further, the plurality of rib members include,at least, a first rib member extending in a first direction and a secondrib member extending in a different, second direction. Moreover, thefirst rib member has a varying height along a length thereof.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 illustrates a perspective view of one embodiment of a windturbine according to the present disclosure;

FIG. 2 illustrates a perspective view of one embodiment of a rotor bladeof a wind turbine according to the present disclosure;

FIG. 3 illustrates an exploded view of the modular rotor blade of FIG.2;

FIG. 4 illustrates a cross-sectional view of one embodiment of a leadingedge segment of a modular rotor blade according to the presentdisclosure;

FIG. 5 illustrates a cross-sectional view of one embodiment of atrailing edge segment of a modular rotor blade according to the presentdisclosure;

FIG. 6 illustrates a cross-sectional view of the modular rotor blade ofFIG. 2 according to the present disclosure;

FIG. 7 illustrates a cross-sectional view of the modular rotor blade ofFIG. 2 according to the present disclosure;

FIG. 8 illustrates a side view of one embodiment of a mold of a rotorblade panel, particularly illustrating an outer skin placed in the moldwith a plurality of grid structures printed thereto;

FIG. 9 illustrates a perspective view of one embodiment of a gridstructure according to the present disclosure;

FIG. 10 illustrates a perspective view of one embodiment of a mold of arotor blade panel with a three-dimensional printer positioned above themold so as to print a grid structure thereto according to the presentdisclosure;

FIG. 11 illustrates a perspective view of one embodiment of a mold of arotor blade panel with a three-dimensional printer positioned above themold and printing an outline of a grid structure thereto according tothe present disclosure;

FIG. 12 illustrates a perspective view of one embodiment of a mold of arotor blade panel with a three-dimensional printer positioned above themold and printing a grid structure thereto according to the presentdisclosure;

FIG. 13 illustrates a cross-sectional view of one embodiment of a firstrib member of a grid structure according to the present disclosure;

FIG. 14 illustrates a cross-sectional view of another embodiment of afirst rib member of a grid structure according to the presentdisclosure;

FIG. 15 illustrates a top view of one embodiment of a grid structureaccording to the present disclosure;

FIG. 16 illustrates a cross-sectional view of one embodiment of a firstrib member and intersecting second rib members of a grid structureaccording to the present disclosure;

FIG. 17 illustrates a side view of one embodiment of a second rib memberof a grid structure according to the present disclosure;

FIG. 18 illustrates a top view of one embodiment of a grid structureaccording to the present disclosure, particularly illustrating ribmembers of the grid structure arranged in a random pattern;

FIG. 19 illustrates a perspective view of another embodiment of a gridstructure according to the present disclosure, particularly illustratingrib members of the grid structure arranged in a random pattern;

FIG. 20 illustrates a perspective view of another embodiment of the gridstructure according to the present disclosure, particularly illustratinga grid structure having curved rib members;

FIG. 21 illustrates a graph of one embodiment of buckling load factor(y-axis) versus weight ratio (x-axis) of a grid structure according tothe present disclosure;

FIG. 22 illustrates a partial, top view of one embodiment of a printedgrid structure according to the present disclosure, particularlyillustrating a node of the grid structure;

FIG. 23 illustrates a partial, top view of one embodiment of a printedgrid structure according to the present disclosure, particularlyillustrating a start printing location and an end printing location ofthe grid structure;

FIG. 24 illustrates an elevation view of one embodiment of a printed ribmember of a grid structure according to the present disclosure,particularly illustrating a base section of one of the rib members ofthe grid structure having a wider and thinner cross-section than theremainder of the rib member so as to improve bonding of the gridstructure to the outer skins of the rotor blade panel;

FIG. 25 illustrates a top view of another embodiment of a grid structureaccording to the present disclosure, particularly illustratingadditional features printed to the grid structure;

FIG. 26 illustrates a cross-sectional view of one embodiment of a rotorblade having a printed grid structure arranged therein according to thepresent disclosure, particularly illustrating alignment features printedto the grid structure for receiving the spar caps and shear web;

FIG. 27 illustrates a partial, cross-sectional view of the rotor bladeof FIG. 25, particularly illustrating additional features printed to thegrid structure for controlling adhesive squeeze out;

FIG. 28 illustrates a cross-sectional view of one embodiment of a rotorblade having printed grid structures arranged therein according to thepresent disclosure, particularly illustrating male and female panelalignment features printed to the grid structure;

FIG. 29 illustrates a top view of yet another embodiment of a gridstructure according to the present disclosure, particularly illustratingauxiliary features printed to the grid structure;

FIG. 30 illustrates a cross-sectional view of one embodiment of a rotorblade panel according to the present disclosure, particularlyillustrating a plurality of grid structures printed to inner surfaces ofthe rotor blade panel; and

FIG. 31 illustrates a partial, cross-sectional view of the leading edgeof the rotor blade panel of FIG. 30, particularly illustrating aplurality of adhesive gaps.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

Generally, the present disclosure is directed to methods formanufacturing grid structures for wind turbine rotor blades usingautomated deposition of materials via technologies such as 3-D Printing,additive manufacturing, automated fiber deposition, as well as othertechniques that utilize CNC control and multiple degrees of freedom todeposit material. As such, the grid structures of the present disclosureare useful for reinforcing an outer skin for a wind turbine rotor blade.The grid shape can be optimized for maximum buckling load factor versusweight and print speed. Further, additive manufacturing allows for morecustomized reinforcement compared to conventional sandwich panels.

Thus, the methods described herein provide many advantages not presentin the prior art. For example, the methods of the present disclosureprovide the ability to easily customize blade structures having variouscurvatures, aerodynamic characteristics, strengths, stiffness, etc. Assuch, the printed structures of the present disclosure can be designedto match the stiffness and/or buckling resistance of existing sandwichpanels for rotor blades. More specifically, the rotor blades andcomponents thereof of the present disclosure can be more easilycustomized based on the local buckling resistance needed. Still furtheradvantages include the ability to locally and temporarily buckle toreduce loads and/or tune the resonant frequency of the rotor blades toavoid problem frequencies. Moreover, the grid structures describedherein enable bend-twist coupling of the rotor blade.

In addition, the methods of the present disclosure provide a high levelof automation, faster throughput, and reduced tooling costs and/orhigher tooling utilization. Further, the rotor blade components of thepresent disclosure may not require adhesives, especially those producedwith thermoplastic materials, thereby eliminating cost, quality issues,and extra weight associated with bond paste.

Referring now to the drawings, FIG. 1 illustrates one embodiment of awind turbine 10 according to the present disclosure. As shown, the windturbine 10 includes a tower 12 with a nacelle 14 mounted thereon. Aplurality of rotor blades 16 are mounted to a rotor hub 18, which is inturn connected to a main flange that turns a main rotor shaft. The windturbine power generation and control components are housed within thenacelle 14. The view of FIG. 1 is provided for illustrative purposesonly to place the present invention in an exemplary field of use. Itshould be appreciated that the invention is not limited to anyparticular type of wind turbine configuration. In addition, the presentinvention is not limited to use with wind turbines, but may be utilizedin any application having rotor blades. Further, the methods describedherein may also apply to manufacturing any similar structure thatbenefits from printing a structure directly to skins within a moldbefore the skins have cooled so as to take advantage of the heat fromthe skins to provide adequate bonding between the printed structure andthe skins. As such, the need for additional adhesive or additionalcuring is eliminated.

Referring now to FIGS. 2 and 3, various views of a rotor blade 16according to the present disclosure are illustrated. As shown, theillustrated rotor blade 16 has a segmented or modular configuration. Itshould also be understood that the rotor blade 16 may include any othersuitable configuration now known or later developed in the art. Asshown, the modular rotor blade 16 includes a main blade structure 15constructed, at least in part, from a thermoset and/or a thermoplasticmaterial and at least one blade segment 21 configured with the mainblade structure 15. More specifically, as shown, the rotor blade 16includes a plurality of blade segments 21. The blade segment(s) 21 mayalso be constructed, at least in part, from a thermoset and/or athermoplastic material.

The thermoplastic rotor blade components and/or materials as describedherein generally encompass a plastic material or polymer that isreversible in nature. For example, thermoplastic materials typicallybecome pliable or moldable when heated to a certain temperature andreturns to a more rigid state upon cooling. Further, thermoplasticmaterials may include amorphous thermoplastic materials and/orsemi-crystalline thermoplastic materials. For example, some amorphousthermoplastic materials may generally include, but are not limited to,styrenes, vinyls, cellulosics, polyesters, acrylics, polysulphones,and/or imides. More specifically, exemplary amorphous thermoplasticmaterials may include polystyrene, acrylonitrile butadiene styrene(ABS), polymethyl methacrylate (PMMA), glycolised polyethyleneterephthalate (PET-G), polycarbonate, polyvinyl acetate, amorphouspolyamide, polyvinyl chlorides (PVC), polyvinylidene chloride,polyurethane, or any other suitable amorphous thermoplastic material. Inaddition, exemplary semi-crystalline thermoplastic materials maygenerally include, but are not limited to polyolefins, polyamides,fluropolymer, ethyl-methyl acrylate, polyesters, polycarbonates, and/oracetals. More specifically, exemplary semi-crystalline thermoplasticmaterials may include polybutylene terephthalate (PBT), polyethyleneterephthalate (PET), polypropylene, polyphenyl sulfide, polyethylene,polyamide (nylon), polyetherketone, or any other suitablesemi-crystalline thermoplastic material.

Further, the thermoset components and/or materials as described hereingenerally encompass a plastic material or polymer that is non-reversiblein nature. For example, thermoset materials, once cured, cannot beeasily remolded or returned to a liquid state. As such, after initialforming, thermoset materials are generally resistant to heat, corrosion,and/or creep. Example thermoset materials may generally include, but arenot limited to, some polyesters, some polyurethanes, esters, epoxies, orany other suitable thermoset material.

In addition, as mentioned, the thermoplastic and/or the thermosetmaterial as described herein may optionally be reinforced with a fibermaterial, including but not limited to glass fibers, carbon fibers,polymer fibers, wood fibers, bamboo fibers, ceramic fibers, nanofibers,metal fibers, or similar or combinations thereof. In addition, thedirection of the fibers may include multi-axial, unidirectional,biaxial, triaxial, or any other another suitable direction and/orcombinations thereof. Further, the fiber content may vary depending onthe stiffness required in the corresponding blade component, the regionor location of the blade component in the rotor blade 16, and/or thedesired weldability of the component.

More specifically, as shown, the main blade structure 15 may include anyone of or a combination of the following: a pre-formed blade rootsection 20, a pre-formed blade tip section 22, one or more one or morecontinuous spar caps 48, 50, 51, 53, one or more shear webs 35 (FIGS.6-7), an additional structural component 52 secured to the blade rootsection 20, and/or any other suitable structural component of the rotorblade 16. Further, the blade root section 20 is configured to be mountedor otherwise secured to the rotor 18 (FIG. 1). In addition, as shown inFIG. 2, the rotor blade 16 defines a span 23 that is equal to the totallength between the blade root section 20 and the blade tip section 22.As shown in FIGS. 2 and 6, the rotor blade 16 also defines a chord 25that is equal to the total length between a leading edge 24 of the rotorblade 16 and a trailing edge 26 of the rotor blade 16. As is generallyunderstood, the chord 25 may generally vary in length with respect tothe span 23 as the rotor blade 16 extends from the blade root section 20to the blade tip section 22.

Referring particularly to FIGS. 2-4, any number of blade segments 21 orpanels having any suitable size and/or shape may be generally arrangedbetween the blade root section 20 and the blade tip section 22 along alongitudinal axis 27 in a generally span-wise direction. Thus, the bladesegments 21 generally serve as the outer casing/covering of the rotorblade 16 and may define a substantially aerodynamic profile, such as bydefining a symmetrical or cambered airfoil-shaped cross-section. Inadditional embodiments, it should be understood that the blade segmentportion of the blade 16 may include any combination of the segmentsdescribed herein and are not limited to the embodiment as depicted. Inaddition, the blade segments 21 may be constructed of any suitablematerials, including but not limited to a thermoset material or athermoplastic material optionally reinforced with one or more fibermaterials. More specifically, in certain embodiments, the blade panels21 may include any one of or combination of the following: pressureand/or suction side segments 44, 46, (FIGS. 2 and 3), leading and/ortrailing edge segments 40, 42 (FIGS. 2-6), a non-jointed segment, asingle-jointed segment, a multi-jointed blade segment, a J-shaped bladesegment, or similar.

More specifically, as shown in FIG. 4, the leading edge segments 40 mayhave a forward pressure side surface 28 and a forward suction sidesurface 30. Similarly, as shown in FIG. 5, each of the trailing edgesegments 42 may have an aft pressure side surface 32 and an aft suctionside surface 34. Thus, the forward pressure side surface 28 of theleading edge segment 40 and the aft pressure side surface 32 of thetrailing edge segment 42 generally define a pressure side surface of therotor blade 16. Similarly, the forward suction side surface 30 of theleading edge segment 40 and the aft suction side surface 34 of thetrailing edge segment 42 generally define a suction side surface of therotor blade 16. In addition, as particularly shown in FIG. 6, theleading edge segment(s) 40 and the trailing edge segment(s) 42 may bejoined at a pressure side seam 36 and a suction side seam 38. Forexample, the blade segments 40, 42 may be configured to overlap at thepressure side seam 36 and/or the suction side seam 38. Further, as shownin FIG. 2, adjacent blade segments 21 may be configured to overlap at aseam 54. Thus, where the blade segments 21 are constructed at leastpartially of a thermoplastic material, adjacent blade segments 21 can bewelded together along the seams 36, 38, 54, which will be discussed inmore detail herein. Alternatively, in certain embodiments, the varioussegments of the rotor blade 16 may be secured together via an adhesive(or mechanical fasteners) configured between the overlapping leading andtrailing edge segments 40, 42 and/or the overlapping adjacent leading ortrailing edge segments 40, 42.

In specific embodiments, as shown in FIGS. 2-3 and 6-7, the blade rootsection 20 may include one or more longitudinally extending spar caps48, 50 infused therewith. For example, the blade root section 20 may beconfigured according to U.S. application Ser. No. 14/753,155 filed Jun.29, 2015 entitled “Blade Root Section for a Modular Rotor Blade andMethod of Manufacturing Same” which is incorporated herein by referencein its entirety.

Similarly, the blade tip section 22 may include one or morelongitudinally extending spar caps 51, 53 infused therewith. Morespecifically, as shown, the spar caps 48, 50, 51, 53 may be configuredto be engaged against opposing inner surfaces of the blade segments 21of the rotor blade 16. Further, the blade root spar caps 48, 50 may beconfigured to align with the blade tip spar caps 51, 53. Thus, the sparcaps 48, 50, 51, 53 may generally be designed to control the bendingstresses and/or other loads acting on the rotor blade 16 in a generallyspan-wise direction (a direction parallel to the span 23 of the rotorblade 16) during operation of a wind turbine 10. In addition, the sparcaps 48, 50, 51, 53 may be designed to withstand the span-wisecompression occurring during operation of the wind turbine 10. Further,the spar cap(s) 48, 50, 51, 53 may be configured to extend from theblade root section 20 to the blade tip section 22 or a portion thereof.Thus, in certain embodiments, the blade root section 20 and the bladetip section 22 may be joined together via their respective spar caps 48,50, 51, 53.

In addition, the spar caps 48, 50, 51, 53 may be constructed of anysuitable materials, e.g. a thermoplastic or thermoset material orcombinations thereof. Further, the spar caps 48, 50, 51, 53 may bepultruded from thermoplastic or thermoset resins. As used herein, theterms “pultruded,” “pultrusions,” or similar generally encompassreinforced materials (e.g. fibers or woven or braided strands) that areimpregnated with a resin and pulled through a stationary die such thatthe resin cures or undergoes polymerization. As such, the process ofmanufacturing pultruded members is typically characterized by acontinuous process of composite materials that produces composite partshaving a constant cross-section. Thus, the pre-cured composite materialsmay include pultrusions constructed of reinforced thermoset orthermoplastic materials. Further, the spar caps 48, 50, 51, 53 may beformed of the same pre-cured composites or different pre-curedcomposites. In addition, the pultruded components may be produced fromrovings, which generally encompass long and narrow bundles of fibersthat are not combined until joined by a cured resin.

Referring to FIGS. 6-7, one or more shear webs 35 may be configuredbetween the one or more spar caps 48, 50, 51, 53. More particularly, theshear web(s) 35 may be configured to increase the rigidity in the bladeroot section 20 and/or the blade tip section 22. Further, the shearweb(s) 35 may be configured to close out the blade root section 20.

In addition, as shown in FIGS. 2 and 3, the additional structuralcomponent 52 may be secured to the blade root section 20 and extend in agenerally span-wise direction so as to provide further support to therotor blade 16. For example, the structural component 52 may beconfigured according to U.S. application Ser. No. 14/753,150 filed Jun.29, 2015 entitled “Structural Component for a Modular Rotor Blade” whichis incorporated herein by reference in its entirety. More specifically,the structural component 52 may extend any suitable distance between theblade root section 20 and the blade tip section 22. Thus, the structuralcomponent 52 is configured to provide additional structural support forthe rotor blade 16 as well as an optional mounting structure for thevarious blade segments 21 as described herein. For example, in certainembodiments, the structural component 52 may be secured to the bladeroot section 20 and may extend a predetermined span-wise distance suchthat the leading and/or trailing edge segments 40, 42 can be mountedthereto.

Referring now to FIGS. 8-19, the present disclosure is directed tomethods for manufacturing rotor blade panels 21 having at least oneprinted reinforcement grid structure 62 formed via 3-D printing, e.g.such as the blade segments illustrated in FIGS. 2-7. As such, in certainembodiments, the rotor blade panel 21 may include a pressure sidesurface, a suction side surface, a trailing edge segment, a leading edgesegment, or combinations thereof. 3-D printing, as used herein, isgenerally understood to encompass processes used to synthesizethree-dimensional objects in which successive layers of material areformed under computer control to create the objects. As such, objects ofalmost any size and/or shape can be produced from digital model data. Itshould further be understood that the methods of the present disclosureare not limited to 3-D printing, but rather, may also encompass morethan three degrees of freedom such that the printing techniques are notlimited to printing stacked two-dimensional layers, but are also capableof printing curved shapes.

Referring particularly to FIG. 10, one embodiment of the method includesplacing a mold 58 of the rotor blade panel 21 relative to a CNC device60. More specifically, as shown in the illustrated embodiment, themethod may include placing the mold 58 into a bed 61 of the CNC device60. Alternatively, the method may include placing the mold 58 under theCNC device 60 or adjacent the CNC device 60. Further, as shown in FIGS.8 and 10, the method of the present disclosure further includes formingone or more fiber-reinforced outer skins 56 in the mold 58 of the rotorblade panel 21. In certain embodiments, the outer skin(s) 56 may includeone or more continuous, multi-axial (e.g. biaxial) fiber-reinforcedthermoplastic or thermoset outer skins. Further, in particularembodiments, the method of forming the fiber-reinforced outer skins 56may include at least one of injection molding, 3-D printing, 2-Dpultrusion, 3-D pultrusion, thermoforming, vacuum forming, pressureforming, bladder forming, automated fiber deposition, automated fibertape deposition, or vacuum infusion.

In addition, as shown, the outer skin(s) 56 of the rotor blade panel 21may be curved. In such embodiments, the method may include forming thecurvature of the fiber-reinforced outer skins 56. Such forming mayinclude providing one or more generally flat fiber-reinforced outerskins, forcing the outer skins 56 into a desired shape corresponding toa desired contour, and maintaining the outer skins 56 in the desiredshape during printing and depositing. As such, the outer skins 56generally retain their desired shape when the outer skins 56 and thegrid structure 62 printed thereto are released. In addition, the CNCdevice 60 may be adapted to include a tooling path that follows thecontour of the rotor blade panel 21.

The method also includes printing and depositing the grid structure 62directly to the fiber-reinforced outer skin(s) 56 via the CNC device 60.More specifically, as shown in FIGS. 9, 10, 12, and 15, the CNC device60 is configured to print and deposit a plurality of rib members 64 thatintersect at a plurality of nodes 74 to form the grid structure 62 ontoan inner surface of the one or more fiber-reinforced outer skins 56.Alternatively, as shown in FIG. 20, the CNC device 60 may also print anddeposit curved rib members 64 that do not intersect to form the gridstructure 62. In other words, any suitable shape of grid structure canbe printed and deposited as desired. As such, in certain embodiments,the grid structure 62 may bond to the fiber-reinforced outer skin(s) 56as the structure 62 is being deposited, which eliminates the need foradditional adhesive and/or curing time.

For example, in one embodiment, the CNC device 60 is configured to printand deposit the rib members 64 onto the inner surface of the one or morefiber-reinforced outer skins 56 after the formed skin(s) 56 reach adesired state that enables bonding of the printed rib members 64thereto, i.e. based on one or more parameters of temperature, time,and/or hardness. Therefore, in certain embodiments, wherein the skin(s)56 and the grid structure 62 are formed of a thermoplastic matrix, theCNC device 60 may immediately print the rib members 64 thereto as theforming temperature of the skin(s) 56 and the desired printingtemperature to enable thermoplastic welding/bonding can be the same).More specifically, in particular embodiments, before the skin(s) 56 havecooled from forming, (i.e. while the skins are still hot or warm), theCNC device 60 is configured to print and deposit the rib members 64 ontothe inner surface of the one or more fiber-reinforced outer skins 56.For example, in one embodiment, the CNC device 60 is configured to printand deposit the rib members 64 onto the inner surface of the outer skins56 before the skins 56 have completely cooled. In addition, in anotherembodiment, the CNC device 60 is configured to print and deposit the ribmembers 64 onto the inner surface of the outer skins 56 when the skins56 have partially cooled. Thus, suitable materials for the gridstructure 62 and the outer skins 56 can be chosen such that the gridstructure 62 bonds to the outer skins 56 during deposition. Accordingly,the grid structure 62 described herein may be printed using the samematerials or different materials.

For example, in one embodiment, a thermoset material may be infused intothe fiber material on the mold 58 to form the outer skins 56 usingvacuum infusion. As such, the vacuum bag is removed after curing and theone or more thermoset grid structures 62 can then be printed onto theinner surface of the outer skins 56. Alternatively, the vacuum bag maybe left in place after curing. In such embodiments, the vacuum bagmaterial can be chosen such that the material would not easily releasefrom the cured thermoset fiber material. Such materials, for example,may include a thermoplastic material such as polymethyl methacrylate(PMMA) or polycarbonate film. Thus, the thermoplastic film that is leftin place allows for bonding of thermoplastic grid structures 62 to thethermoset skins with the film in between.

In still further embodiments, the outer skins 56 may be formed of areinforced thermoplastic resin with the grid structure 62 being formedof a thermoset-based resin with optional fiber reinforcement. In suchembodiments, depending on the thermoset chemistry involved—the gridstructure 62 may be printed to the outer skins 56 while the skins 56 arestill hot, warm, partially cooled, or completely cooled.

In addition, the method of the present disclosure may include treatingthe outer skins 56 to promote bonding between the outer skins 56 and thegrid structure 62. More specifically, in certain embodiments, the outerskins 56 may be treated using flame treating, plasma treating, chemicaltreating, chemical etching, mechanical abrading, embossing, elevating atemperature of at least areas to be printed on the outer skins 56,and/or any other suitable treatment method to promote said bonding. Inadditional embodiments, the method may include forming the outer skins56 with more (or even less) matrix resin material on the inside surfaceto promote said bonding. In additional embodiments, the method mayinclude varying the outer skin thickness and/or fiber content, as wellas the fiber orientation.

Further, the method of the present disclosure includes varying thedesign of the grid structure 62 (e.g. materials, width, height,thickness, shapes, etc., or combinations thereof). As such, the gridstructure 62 may define any suitable shape so as to form any suitablestructure component, such as the spar cap 48, 50, the shear web 35, oradditional structural components 52 of the rotor blade 16. For example,as shown in FIG. 11, the CNC device 60 may begin printing the gridstructure 62 by first printing an outline of the structure 62 andbuilding up the grid structure 62 with the rib members 64 in multiplepasses. As such, extruders 65 of the CNC device 60 can be designed haveany suitable thickness or width so as to disperse a desired amount ofresin material to create rib members 64 with varying heights and/orthicknesses. Further, the grid size can be designed to allow localbuckling of the face sheet in between the rib members 64, which caninfluence the aerodynamic shape as an extreme (gust) load mitigationdevice.

More specifically, as shown in FIGS. 9-15, the rib members 64 mayinclude, at least, a first rib member 66 extending in a first direction76 and a second rib member 68 extending in a different, second direction78. In several embodiments, as shown in FIG. 15, the first direction 76of the first set 70 of rib members 64 may be generally perpendicular tothe second direction 78. More specifically, in certain embodiments, thefirst direction 76 may be generally parallel to a chord-wise directionof the rotor blade 16 (i.e. a direction parallel to the chord 25 (FIG.2)), whereas the second direction 78 of the second set 72 of rib members64 may be generally parallel with a span-wise direction of the rotorblade 16 (i.e. a direction parallel to the span 23 (FIG. 2)).Alternatively, in one embodiment, an off-axis orientation (e.g. fromabout 20° to about 70°) may be provided in the grid structure 62 tointroduce bend-twist coupling to the rotor blade 16, which can bebeneficial as passive load mitigation device. Alternatively, the gridstructure 62 may be parallel the spar caps 48, 50.

Moreover, as shown in FIGS. 13 and 14, one or more of the first andsecond rib member(s) 66, 68 may be printed to have a varying heightalong a length 84, 85 thereof. In alternative embodiments, as shown inFIGS. 16 and 17, one or more of the first and second rib member(s) 66,68 may be printed to have a uniform height 90 along a length 84, 85thereof. In addition, as shown in FIGS. 9, 12, and 15, the rib members64 may include a first set 70 of rib members 64 (that contains the firstrib member 66) and a second set 72 of rib members 64 (that contains thesecond rib member 68).

In such embodiments, as shown in FIGS. 13 and 14, the method may includeprinting a maximum height 80 of either or both of the first set 70 ofrib members 64 or the second set 72 of rib members 64 at a locationsubstantially at (i.e. +/−10%) a maximum bending moment in the rotorblade panel 21 occurs. For example, in one embodiment, the maximumbending moment may occur at a center location 82 of the grid structure62 though not always. As used herein, the term “center location”generally refers to a location of the rib member 64 that contains thecenter plus or minus a predetermined percentage of an overall length 84of the rib member 64. For example, as shown in FIG. 13, the centerlocation 82 includes the center of the rib member 64 plus or minus about10%. Alternatively, as shown in FIG. 14, the center location 82 includesthe center plus or minus about 80%. In further embodiments, the centerlocation 82 may include less than plus or minus 10% from the center orgreater than plus or minus 80% of the center.

In addition, as shown, the first and second sets 70, 72 of rib members64 may also include at least one tapering end 86, 88 that tapers fromthe maximum height 80. More specifically, as shown, the tapering end(s)86, 88 may taper towards the inner surface of the fiber-reinforced outerskins 56. Such tapering may correspond to certain blade locationsrequiring more or less structural support. For example, in oneembodiment, the rib members 64 may be shorter at or near the blade tipand may increase as the grid structure 62 approaches the blade root. Incertain embodiments, as shown particularly in FIG. 14, a slope of thetapering end(s) 86, 88 may be linear. In alternative embodiments, asshown in FIG. 13, the slope of the tapering end(s) 86, 88 may benon-linear. In such embodiments, the tapering end(s) 86, 88 provide animproved stiffness versus weight ratio of the panel 21.

In additional embodiments, one or more heights of intersecting ribmembers 64 at the nodes 74 may be different. For example, as shown inFIG. 16, the heights of the second set 72 of rib members 64 aredifferent than the intersecting first rib member 66. In other words, therib members 64 can have different heights for the different directionsat their crossing points. For example, in one embodiment, the span-wisedirection rib members 64 may have a height twice as tall as the heightof the chord-wise direction rib members 64. In addition, as shown inFIG. 16, the second set 72 of rib members 64 may each have a differentheight from adjacent rib members 64 in the second set 72 of rib members64. In such embodiments, as shown, the method may include printing eachof the second set 70 of rib members 64 such that structures 64 havinggreater heights are located towards the center location 82 of the gridstructure 62. In addition, the second set 70 of rib members 64 may betapered along a length 85 thereof such that the rib members 64 aretapered shorter as the rib members approach the blade tip.

In further embodiments, as mentioned, the rib members 64 may be printedwith varying thicknesses. For example, as shown in FIG. 15, the firstset 70 of rib members 64 define a first thickness 94 and the second set72 of rib members 64 define a second thickness 96. More specifically, asshown, the first and second thicknesses 94, 96 are different. Inaddition, as shown in FIGS. 18 and 19, the thicknesses of a single ribmember 64 may vary along its length.

Referring particularly to FIG. 15, the first set 70 of rib members 64and/or the second set 72 of rib members 64 may be evenly spaced. Inalternative embodiments, as shown in FIGS. 18 and 19, the first set 70of rib members 64 and/or the second set 72 of rib members 64 may beunevenly spaced. For example, as shown, the additive methods describedherein enable complex inner structures that can be optimized for loadsand/or geometric constraints of the overall shape of the rotor bladepanel 21. As such, the grid structure 62 of the present disclosure mayhave shapes similar to those occurring in nature, such as organicstructures (e.g. bird bones, leaves, trunks, or similar). Accordingly,the grid structure 62 can be printed to have an inner blade structurethat optimizes stiffness and strength, while also minimizing weight. Instill another embodiment, as shown in FIG. 20, the grid structure 62 mayinclude at least one curved rib member 64. More specifically, as shown,the grid structure 62 includes a plurality of curved rib members 64.Further, as shown, the curved rib member(s) may form a waveform.

In several embodiments, the cycle time of printing the rib members 64can also be reduced by using a rib pattern that minimizes the amount ofdirectional change. For example, 45-degree angled grids can likely beprinted faster than 90-degree grids relative to the chord direction ofthe proposed printer, for example. As such, the present disclosureminimizes printer acceleration and deceleration where possible whilestill printing quality rib members 64.

In another embodiment, as shown in FIGS. 8 and 12, the method mayinclude printing a plurality of grid structures 62 onto the innersurface of the fiber-reinforced outer skins 56. More specifically, asshown, the plurality of grid structures 62 may be printed in separateand distinct locations on the inner surface of the outer skins 56.

Certain advantages associated with the grid structure 62 of the presentdisclosure can be better understood with respect to FIG. 21. As shown,the graph 100 illustrates the stability of the rotor blade 16(represented as the buckling load factor “BLF”) on the y-axis versus theweight ratio on the x-axis. Curve 102 represents the stability versusthe weight ratio for a conventional sandwich panel rotor blade. Curve104 represents the stability versus the weight ratio for a rotor bladehaving a non-tapered grid structure constructed of short fibers. Curve106 represents the stability versus the weight ratio for a rotor bladehaving a non-tapered grid structure without fibers. Curve 108 representsthe stability versus the weight ratio for a rotor blade having a gridstructure 62 constructed of tapered rib members 64 with 1:3 slope andwithout fibers. Curve 110 represents the stability versus the weightratio for a rotor blade having a grid structure 62 constructed oftapered rib members 64 with 1:2 slope and without fibers. Curve 112represents the stability versus the weight ratio for a rotor blade 16having a grid structure 62 containing short fibers having a firstthickness and being constructed of tapered rib members 64 with 1:3slope. Curve 114 represents the stability versus the weight ratio for arotor blade 16 having a grid structure 62 containing short fibers havinga second thickness that is less than the first thickness and beingconstructed of tapered rib members 64 with 1:3 slope. Thus, as shown,rib members 64 containing fibers maximize the modulus thereof, whilethinner rib members minimize the weight added to the rotor blade 16. Inaddition, as shown, higher taper ratios increase the buckling loadfactor.

Referring now to FIGS. 22-24, various additional features of the gridstructure 62 of the present disclosure are illustrated. Morespecifically, FIG. 22 illustrates a partial, top view of one embodimentof the printed grid structure 62, particularly illustrating one of thenodes 74 thereof. As shown, the CNC device 60 may form at least onesubstantially 45-degree angle 95 for a short distance at one or more ofthe plurality of nodes 74. As such, the 45-degree angle 95 is configuredto increase the amount of abutment or bonding at the corners. In suchembodiments, as shown, there may be a slight overlap in this cornernode.

Referring particularly to FIG. 23, a partial, top view of one embodimentof the printed grid structure 62 is illustrated, particularlyillustrating a start printing location and an end printing location ofthe grid structure 62. This helps with the startup and stop of printingthe ribs. When the CNC device 60 begins to print the rib members 64 andthe process accelerates, the extruders may not perfectly extrude theresin material. Thus, as shown, the CNC device 60 may start the printingprocess with a curve or swirl to provide a lead in for the rib structure64. By extruding this swirl at the start location, the extruders 65 aregiven time to more slowly ramp up/down their pressure, instead of beingrequired to instantaneously start on top of a narrow freestandingstarting point. As such, the swirl allows for the grid structures 65 ofthe present disclosure to be printed at higher speeds.

In certain instances, however, this start curve may create a small void99 (i.e. the area within the swirl) in the start region which can createissues as the void 99 propagates up through ongoing layers. Accordingly,the CNC device 60 is also configured to end one of the rib members 64within the swirl of the start region so as to prevent the void 99 fromdeveloping. More specifically, as shown, the CNC device 60 essentiallyfills the start curve of the one of the rib members 64 with an endlocation of another rib member 64.

Referring particularly to FIG. 24, an elevation view of one embodimentof one of the rib members 64 of the printed grid structure 62 isillustrated, particularly illustrating a base section 55 of the ribmembers 64 having a wider W and thinner T first layer so as to improvebonding of the grid structure 62 to the outer skins 56 of the rotorblade panel 21. To form this base section 55, the CNC device 60 prints afirst layer of the grid structure 62 such that the individual basesections 55 define a cross-section that is wider and thinner than therest of the cross-section of the rib members 64. In other words, thewider and thinner base section 55 of the rib members 64 provides alarger surface area for bonding to the outer skins 56, maximum heattransfer to the outer skins 56, and allows the CNC device 60 to operateat faster speeds on the first layer. In addition, the base section 55may minimize stress concentrations at the bond joint between thestructure 62 and the outer skins 56.

Referring now to FIGS. 25-30, the CNC device 60 described herein is alsoconfigured to print at least one additional feature 63 directly to thegrid structure(s) 62, wherein heat from the printing bonds theadditional features 63 to the structure 62. As such, the additionalfeature(s) 63 can be directly 3-D printed into the grid structure 62.Such printing allows for the additional feature(s) 63 to be printed intothe grid structure 62 using undercuts and/or negative draft angles asneeded. In addition, in certain instances, hardware for various bladesystems can be assembled within the grid structure 62 and then printedover to encapsulate/protect such components.

For example, as shown in FIGS. 25-28, the additional feature(s) 63 mayinclude auxiliary features 81 and/or assembly features 69. Morespecifically, as shown in FIGS. 25 and 26, the assembly feature(s) 69may include one or more alignment structures 73, at least one handlingor lift feature 71, one or more adhesive gaps or standoffs 95, or one ormore adhesive containment areas 83. For example, in one embodiment, theCNC device 60 is configured to print a plurality of handling features 71to the grid structure 62 to provide multiple gripping locations forremoving the rotor blade panel 21 from the mold 58. Further, as shown inFIG. 25, one or more adhesive containment areas 83 may be formed intothe grid structure 62, e.g. such that another blade component can besecured thereto or thereby.

In particular embodiments, as shown in FIGS. 26 and 27, the alignment orlead in structure(s) 73 may include any spar cap and/or shear webalignment features. In such embodiments, as shown, the grid structure(s)62 may printed such that an angle of the plurality of rib members 64 isoffset from a spar cap location so as to create an adhesive containmentarea 83. More specifically, as shown, the adhesive containment areas 83are configured to prevent squeeze out of an adhesive 101. It should befurther understood that such adhesive containment areas 83 are notlimited to spar cap locations, but may be provided in any suitablelocation on the grid structure 62, including but not limited tolocations adjacent to the leading edge 24, the trailing edge 26, or anyother bond locations.

In further embodiments, the alignment structure(s) 73 may correspond tosupport alignment features (e.g. for support structure 52), blade jointalignment features, panel alignment features 75, or any other suitablealignment feature. More specifically, as shown in FIG. 28, the panelalignment features 75 may include a male alignment feature 77 or afemale alignment feature 79 that fits with a male alignment feature 77or a female alignment feature 79 of an adjacent rotor blade panel 21.

Further, as shown in FIG. 29, the additional feature(s) 63 may includeat least one auxiliary feature 81 of the rotor blade panel 21. Forexample, in one embodiment, the auxiliary features 81 may include abalance box 67 of the rotor blade 16. In such embodiments, the step ofprinting the additional feature(s) 63 into the grid structure(s) 62 mayinclude enclosing at least a portion of the grid structure 62 to formthe balance box 63 therein.

In addition, the step of printing the additional feature(s) 63 into thegrid structure(s) 62 may also include enclosing an area between the ribmembers 64 to enclose said area. In general, 3-D printing technologiestend to print layers on top of layers, however, the present disclosurealso encompasses printing a layer on top of air by using certain,typically amorphous, polymers, e.g. acrylonitrile butadiene styrene(ABS). In such embodiments, the enclosure can be printed across alimited distance without support therebeneath. Though such structuresmay experience some degree of drooping or sag, the structures enable theprinting of a surface structure to cap off the rib members 64 while alsoproviding additional stiffness to the grid structure 62.

In additional embodiments, the auxiliary feature(s) 81 may includehousings 87, pockets, supports, or enclosures e.g. for an activeaerodynamic device, a friction damping system, or a load control system,ducting 89, channels, or passageways e.g. for deicing systems, one ormore valves, a support 91, tubing, or channel around a hole location ofthe fiber-reinforced outer skins, a sensor system having one or moresensors 103, one or more heating elements 105 or wires 105, rods,conductors, or any other printed feature. In one embodiment, forexample, the supports for the friction damping system may includesliding interface elements and/or free interlocking structures. Forexample, in one embodiment, the 3-D printed grid structure 62 offers theopportunity to easily print channels therein for providing warmed airfrom heat source(s) in the blade root or hub to have a de-icing effector prevent ice formation. Such channels allow for air contact directlywith the outer skins 56 to improve heat transfer performance.

In particular embodiments, the sensor system may be incorporated intothe grid structure(s) 62 and/or the outer skins 56 during themanufacturing process. For example, in one embodiment, the sensor systemmay be a surface pressure measurement system arranged with the gridstructure 62 and/or directly incorporated into the skins 56. As such,the printed structure and/the skins 56 are manufactured to include theseries of tubing/channels needed to easily install the sensor system.Further, the printed structure and/or the skins 56 may also provide aseries of holes therein for receiving connections of the system. Thus,the manufacturing process is simplified by printing various structuresinto the grid structure 62 and/or the skins 56 to house the sensors, actas the static pressure port, and/or act as the tubing that runs directlyto the outer blade skin. Such systems may also enable the use ofpressure taps for closed loop control of the wind turbine 10.

In still further embodiments, the mold 58 may include certain marks(such as a positive mark) that are configured to create a small dimplein the skin during manufacturing. Such marks allow for easy machining ofthe holes in the exact location needed for the associated sensors. Inaddition, additional sensor systems may be incorporated into the gridstructures and/or the outer skin layers 56 to provide aerodynamic oracoustic measurements so as to allow for either closed loop control orprototype measurements.

In addition, the heating elements 105 described herein may be flushsurface mounted heating elements distributed around the blade leadingedge. Such heating elements 105 allow for the determination of the angleof attack on the blade by correlating temperature/convective heattransfer with flow velocity and the stagnation point. Such informationis useful for turbine control and can simplify the measurement process.It should be understood that such heating elements 105 may also beincorporated into the outer skin layers 56 in additional ways and arenot required to be flush mounted therein.

Referring back to FIG. 25, the method according to the presentdisclosure may include placing a filler material 98 between one or moreof the rib members 64. For example, in certain embodiments, the fillermaterial 98 described herein may be constructed of any suitablematerials, including but not limited to low-density foam, cork,composites, balsa wood, composites, or similar. Suitable low-densityfoam materials may include, but are not limited to, polystyrene foams(e.g., expanded polystyrene foams), polyurethane foams (e.g.polyurethane closed-cell foam), polyethylene terephthalate (PET) foams,other foam rubbers/resin-based foams and various other open cell andclosed cell foams. In such embodiments, the method 100 may also includeprinting a top surface over the filler material 98, which eliminates thedroop or sag effect described above.

Referring back to FIG. 28, the method may also include printing one ormore features 93 onto the outer skins 56, e.g. at the trailing and/orleading edges of the rotor blade panels 21. For example, as shown inFIG. 28, the method may include printing at least one lightningprotection feature 93 onto at least one of the one or morefiber-reinforced outer skins 56. In such embodiments, the lightningprotection feature 93 may include a cooling fin or a trailing edgefeature having less fiber content than the fiber-reinforced outer skins56. More specifically, the cooling fins may be directly printed to theinside surface of the outer skins 56 and optionally loaded with fillersto improve thermal conductivity but below a certain threshold to addresslightning related concerns. As such, the cooling fins are configured toimprove thermal transfer from the heated airflow to the outer skins 56.In additional embodiments, such features 93 may be configured tooverlap, e.g. such as interlocking edges or snap fits.

Referring now to FIGS. 30-31, the additional feature(s) 63 may includean adhesive gap 95 or stand-off, which may be incorporated into the gridstructures 62. Such standoffs 95 provide a specified gap between twocomponents when bonded together so to minimize adhesive squeeze out. Assuch, the standoffs 95 provide the desired bond gap for optimized bondstrength based on the adhesive used.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A method for manufacturing a rotor blade skin fora rotor blade of a wind turbine, the method comprising: placing one ormore fiber-reinforced outer skin layers into a mold of the rotor bladeskins; printing and depositing, via a computer numeric control (CNC)device, a plurality of rib members that form at least onethree-dimensional (3-D) reinforcement grid structure onto an innersurface of the one or more fiber-reinforced outer skin layers, the gridstructure bonding to the one or more fiber-reinforced outer skin layersas the grid structure is being printed and deposited; and, printing anddepositing at least one additional feature into the grid structure. 2.The method of claim 1, wherein the at least one additional featurecomprises at least one auxiliary feature of the rotor blade skin or atleast one assembly feature of the rotor blade skin.
 3. The method ofclaim 2, wherein the at least one auxiliary feature comprises at leastone of a balance box, a support, housing, or enclosure for an activeaerodynamic device, ducting or channels for deicing systems, one or moresupports for a friction damping system, one or more supports or pocketsfor a load control system, one or more passageways, one or more valves,supports, tubing, or channels around a hole location of thefiber-reinforced outer skin layers, one or more sensors, one or moreheating elements, a wire, a rod, a conductor, or a lift feature.
 4. Themethod of claim 1, wherein printing the at least one additional featureinto the grid structure further comprises enclosing at least a portionof the grid structure.
 5. The method of claim 2, wherein the at leastone assembly feature comprises at least one of one or more alignmentstructures, at least one handling feature, or one or more adhesivecontainment areas.
 6. The method of claim 5, further comprising printinga plurality of handling features to the grid structure to providemultiple gripping locations for removing the rotor blade skin from themold.
 7. The method of claim 1, further comprising printing the at leastone additional feature into the grid structure using at least one of anundercut or a negative draft angle.
 8. The method of claim 1, furthercomprising printing at least one lightning protection feature onto atleast one of the one or more fiber-reinforced outer skin layers.
 9. Themethod of claim 1, further comprising printing a first layer of the gridstructure to form individual base sections of the plurality of ribmembers, each of the individual base sections defining a cross-sectionthat is wider and thinner than a remainder of the plurality of ribmembers.
 10. The method of claim 1, further comprising forming, via theCNC device, a curve at a start location of a first rib member andfilling the curve with an end location of a second rib member.
 11. Themethod of claim 1, further comprising forming at least one substantially45-degree angle at one or more nodes of the grid structure.